The present invention relates to a damper and a door handle provided with the damper.
Patent Document 1 discloses a damper for generating high torque as shown in FIG. 12, in which through holes 100A are formed in a seat metal plate 100 of an automobile door panel. A pair of pivot arms 106 as a crank member is provided on a backside of an operation handle 102 to be provided on a front side of the seat metal plate 100, so that the pivot arms 106 can be inserted into the through holes 100A.
A pair of projections 104 projects from a backside of the seat metal plate 100. The pivot arms 106 are arranged inside the projections 104 in a state adjacent to the projections 104. Bearing parts 112 with axle holes 110 having a square cross section are rotatably attached to the projections 104.
A cylinder shaped damper 114 has rotation axes 114A with a rectangular shape projecting from both ends thereof for engaging the axle holes 110 and short holes 106A formed in the projections 106, so that the cylinder shaped damper 114 can rotate together with the pivot arms 106.
Accordingly, when the operating handle 102 is pulled to rotate the pivot arms 106 counterclockwise, the bearing parts 112 rotate relative to the projections 104, so that the rotation axes 114A stir viscous fluid in the damper 114, thereby applying torque to the operation handle 102.
A spring 110 is attached to the rotation axes 114 for urging the pivot arms 106 clockwise. When the operation handle 102 rotates clockwise, the torque applied to the operation handle 102 is reduced.
In Patent Document 1, the spring 116 reduces the torque applied to the operation handle 102 only when the operation handle 102 rotates clockwise. The damper 114 does not have a structure for changing torque according to a rotational direction of the operation handle 102.
In Patent Document 2, as shown in FIG. 13, a projection 122 projects from an inner circumference surface of a casing 120 filled with viscous fluid. A rotation member 124 is rotatably supported in the casing 120.
A supporting projection 126 projects from an outside circumference surface of the rotation member 124 along an axial direction of the rotation member 124. A movable valve 128 is retained on a surface of the supporting projection 126 to be movable along a circumferential direction of the casing 120.
When the rotation member 124 rotates in an arrow direction A (counterclockwise), the movable valve 128 receives resistance due to viscous fluid and rotates in a direction opposite to the arrow direction A around the supporting projection 126. A fluid blocking surface 132 at a tip of the movable valve 128 closely contacts an inner surface of the casing 120. Accordingly, a flat portion 136 of the movable valve 128 pushes viscous fluid 134 to flow between the projection 122 and an axial portion 138, thereby generating high torque.
On the other hand, when the rotation member 124 rotates in an arrow direction B, the movable valve 128 receives resistance due to viscous fluid 134 and rotates in a direction opposite to the arrow direction B. The fluid blocking surface 132 of the movable valve 128 moves away from the inner surface of the casing 120. Accordingly, a fluid chamber inside the casing 120 and divided by the movable valve 128 becomes a communicating state. As a result, viscous fluid 134 flows, thereby generating no damping effect.
In Patent Document 2, viscous fluid 134 flows through the space 140 between the projection 122 and the axial portion 138 regardless of the rotational direction of the axial portion 138. Accordingly, viscous fluid 134 flows through the space 140 in both directions to apply at least shear resistance to the axial portion 138. Therefore, the damper effect is somehow generated when the rotation member 124 rotates in the arrow direction B.
In Patent Document 3, a convex portion 152 projects from an outer circumference surface of a rotation member 150 along an axial direction, and a notch 153 is provided at a middle of the convex portion 152 in the axial direction. A valve member 154 engages the convex portion 152, so that the rotation member 150 rotates with a small gap between an outer circumference portion of the rotation member 150 and an inner circumference surface of a casing.
The valve member 154 has vertical walls 158 and 160 at left and right sides, and a notch 162 is formed in the vertical wall 158 along the axial direction. When the rotation member 124 rotates toward the vertical wall 158, a by-path passage of viscous fluid is formed from the notch 162 to the notch 153, thereby reducing torque.
On the other hand, when the rotation member 124 rotates toward the vertical wall 160, the by-path passage of viscous fluid is not formed. Viscous fluid flows only through a space between an upper surface of the valve member 154 and the inner circumference of the casing, and a space between a projection on the inner circumference of the casing and the outer circumference of the rotation member 150, thereby generating large rotational resistance and increasing torque.
A groove 168 is provided at a center of the outer circumference of the rotation member 150 in a circumferential direction. The groove 168 has a constant width and is formed to become deeper from a start area S toward an end area E.
Accordingly, a by-path passage of viscous fluid is formed between an upper surface of the projection and the groove 168. When the rotation member 150 rotates and the start end S faces the upper surface of the projection, the by-path passage has a small cross section in the axial direction, thereby generating high torque. When the end area E faces the upper surface of the projection 166, small torque is generated.
In Patent Document 3, the rotation member 150 and the valve member 154 always rotate together. Accordingly, the by-path passage of viscous fluid is formed between the upper surface of the projection and the groove 168, thereby reducing torque generated on the rotation member 150. However, as compared with a case that only the rotation member 150 rotates, extra torque is generated on the rotation member 150 by an amount of engaging the valve-member 154.                Patent Document 1: U.S. Pat. No. 5,743,575        Patent Document 2: Japanese Patent Publication (Kokai) No. 10-208124        Patent Document 3: Japanese Patent Publication (Kokai) No. 8-109940        
In view of the problems described above, an object of the present invention is to provide a damper and a door handle having the damper, in which it is possible to increase a difference in torque according to a rotational direction.
Further objects and advantages of the invention will be apparent from the following description of the invention.